Abstract
Purpose: :
Dry eye is frequently encountered and often treated with artificial tears (AT). The administration of an AT can disrupt the tear layer resulting in an immediate decrease in contrast sensitivity (CS) and potentially an increase in HOAs. While this immediate effect was shown to be dependent on viscosity of the AT, the longer-term effect of the continuous use of ATs is rarely examined. We previously demonstrated (ARVO 2007) that dry eye subjects exhibited a smaller loss in CS after the administration of a single drop of Optive Lubricant Eye Drops if they had been using them for 2 weeks. This suggested that continued use of this AT may alter the tear layer. The purpose of this study was to determine if long-term use of ATs had an effect on HOAs similar to the effect on CS.
Methods: :
Twenty subjects (10 normal, 10 dry eye) used Optive (Allergan) on a daily basis (minimum 2X per day) for two weeks. The presence of dry eye was assessed by 1. symptoms (Schein questionnaire), 2. tear instability (TBUT), and 3. ocular surface damage (fluorescein staining). The subjects were examined before (i.e., the baseline) and at 1 and 2 weeks after daily AT use. Aberrations were measured with a VISX system. At each visit, ocular aberrations were measured (before AT administration and at 0.5, 1, 3, 5, 10, 15, 20 and 25 minutes after 1 drop of Optive was administered). The difference in HOAs before AT administration compared to 0.5 minutes after AT administration was determined for each visit (baseline, 1 and 2 weeks after AT use).
Results: :
The normal subjects did not display an increase in HOAs with AT administration for the baseline (p = 0.342) or week 1 visit (p = 0.510) but they did on the week 2 visit (p = 0.012). The dry eye subjects displayed a significant increase in HOAs for the baseline (p = 0.002) and week 1 visit (p = 0.028) but not the week 2 visit (p = 0.105).
Conclusions: :
Two weeks' use of Optive by dry eye subjects altered the immediate effect of AT administration on HOAs. This suggests that the changes previously observed in CS are the result of alterations in the HOAs of the tear layer.
Clinical Trial: :
www.clinicaltrials.gov NCT00395759
Keywords: cornea: tears/tear film/dry eye • aberrations • optical properties